The cooling of the Pacific Ocean in the equatorial zone, accompanied by the onset of La Niña conditions, is very likely among the causes of the large-scale disaster involving the devastating wildfires in the Los Angeles region. Other causes include climate change and urban mismanagement.
The conditions for wildfires in January in Southern California are particularly concerning this year. This is because, after two years of abundant moisture, especially during the 2022–2023 period, the 2024–2025 wet season has proven to be notably inconsistent.
While Northern California has experienced exceptionally rainy conditions in recent months, Southern California has faced an almost record-breaking drought with very little rain.
In Los Angeles, the beginning of winter is the driest since 1964. The reference weather station for precipitation in Southern California has recorded only 0.5 mm (0.02 inches) of rain since December 1, and no rainfall is forecast for the days.
This atmospheric pattern aligns with La Niña conditions, currently classified as weak to marginal, which generally bring more rain to the north and drier conditions to the south along the U.S. West Coast.
However, the disparity this winter is greater than typically observed. Data show that in the city of Eureka, Northern California, the rainfall during the October–December 2024 quarter totaled 589 mm (23.2 inches), making it the 12th wettest last quarter of the year in 139 years of records, with the 1991–2020 average for the period being 388 mm (15.3 inches).
Meanwhile, in San Diego, Southern California, rainfall during the October–December 2024 quarter amounted to just 3.5 mm (0.14 inches), the third driest last quarter of the year in 175 years of meteorological records, with the average for the last three months of the year being 75.1 mm (2.96 inches).
Currently, according to data from the National Oceanic and Atmospheric Administration (NOAA), the sea surface temperature anomaly in the Central-East Equatorial Pacific (Niño 3.4 region) is at -0.7°C. This value falls within the range for weak La Niña (-0.5°C to -0.9°C). For five consecutive weeks, this area of the Pacific has shown sea temperature anomalies consistent with La Niña.
